1. Field of the Disclosure
The present invention relates to a method for fabricating a cliché which can prevent formation of a defective thin film pattern, and a method for forming a thin film pattern by using the same.
2. Discussion of the Related Art
Recently, various kinds of flat display devices have been developed, which can reduce weight and volume that are disadvantages of a cathode ray tube. As the flat display device, there is a liquid crystal display device, a field emission display device, a plasma display panel, an electroluminescence EL display device, and so on.
The flat display device is provided with a plurality of thin films formed by mask process including a deposition step, an exposure step, a development step, and etching step, and so on. However, since the mask process as a complicate fabrication process, the mask process increases a production cost. Consequently, researches for forming the thin film by using a printing process utilizing a printing roller are under progress.
The printing process is a process in which a printing liquid is coated on a blanket on the printing roller, a pattern of the printing liquid is formed on the printing roller by using a cliché having a depressed pattern and a relieved pattern, and the pattern of the printing liquid is transcribed to a substrate, thereby forming a desired thin film.
Referring to FIG. 1A, a first depressed pattern 14 matched to a first thin film layer and a second depressed pattern 16 matched to a second thin film layer are formed on the cliche 10 for forming first and second thin film layers of the same material having line widths different from each other.
Referring to FIG. 1B, if the printing roller 20 rolls on the cliche 10, the printing roller 20 is brought into contact A with a bottom surface of the second depressed pattern 16 having the line width greater than the first depressed pattern 14 to transcribe the printing liquid 22 from the printing roller 20 to the bottom surface of the second depressed pattern 16, resulting to lose the printing liquid 22.
Referring to FIG. 1C, if the printing liquid 22 lost thus is transcribed to a substrate 1, the first thin film layer 24, and a pin hole form of a region A in the second thin film layer 26, at which no printing liquid is printed are formed as shown in FIG. 1D. Particularly, if the second thin film layer 26 is used as a black matrix layer or a color filter which is to produce a color, a defective pattern takes place, in which a color is missing showing no color at the region A in the second thin film layer 26.